feat#550375: Support ref struct and readonly ref struct syntaxes (#608)

* Support `ref struct` and `readonly ref struct` syntaxes.

* update

* Refactor code

* Update

mdoc/Consts.cs

@@ -38,12 +38,15 @@ namespace Mono.Documentation
         public const string VoidFullName = "System.Void";
         public const string RefTypeObsoleteString = "Types with embedded references are not supported in this version of your compiler.";
         public const string FrameworksIndexFolderName = "FrameworksIndex";
-        public const string CompilerGeneratedAttribute = "System.Runtime.CompilerServices.CompilerGeneratedAttribute";
-        public const string CompilationMappingAttribute = "Microsoft.FSharp.Core.CompilationMappingAttribute";
         public const string FrameworksIndex = "FrameworksIndex";
         public const string FrameworkAlternate = "FrameworkAlternate";
         public const string Index = "Index";
 
         public static bool CollapseInheritedInterfaces = true;
+
+        public const string CompilationMappingAttribute = "Microsoft.FSharp.Core.CompilationMappingAttribute";
+        public const string CompilerGeneratedAttribute = "System.Runtime.CompilerServices.CompilerGeneratedAttribute";
+        public const string IsByRefLikeAttribute = "System.Runtime.CompilerServices.IsByRefLikeAttribute";
+        public const string IsReadOnlyAttribute = "System.Runtime.CompilerServices.IsReadOnlyAttribute";
     }
 }

mdoc/Mono.Documentation/Updater/DocUtils.cs

@@ -945,5 +945,18 @@ namespace Mono.Documentation.Updater
 
             return type;
         }
+
+        public static bool HasCustomAttribute(ICustomAttributeProvider customAttrProvider, string attributeName)
+        {
+            if (customAttrProvider == null)
+            {
+                return false;
+            }
+            else
+            {
+                return customAttrProvider.HasCustomAttributes
+                    && customAttrProvider.CustomAttributes.Any(attr => attr.AttributeType.FullName == attributeName);
+            }
+        }
     }
 }

mdoc/Mono.Documentation/Updater/Formatters/CSharpFullMemberFormatter.cs

@@ -238,7 +238,19 @@ namespace Mono.Documentation.Updater.Formatters
             if (t.IsEnum)
                 return "enum";
             if (t.IsValueType)
-                return "struct";
+            {
+                StringBuilder buf = new StringBuilder();
+                if (DocUtils.HasCustomAttribute(t, Consts.IsReadOnlyAttribute))
+                {
+                    buf.Append("readonly ");
+                }
+                if (DocUtils.HasCustomAttribute(t, Consts.IsByRefLikeAttribute))
+                {
+                    buf.Append("ref ");
+                }
+                buf.Append("struct");
+                return buf.ToString();
+            }
             if (t.IsClass || t.FullName == "System.Enum")
                 return "class";
             if (t.IsInterface)
@@ -508,8 +520,7 @@ namespace Mono.Documentation.Updater.Formatters
                 modifiers += " ref";
             }
 
-            if (method.ReturnType.IsRequiredModifier
-                && method.MethodReturnType.CustomAttributes.Any(attr => attr.AttributeType.FullName == "System.Runtime.CompilerServices.IsReadOnlyAttribute"))
+            if (method.ReturnType.IsRequiredModifier && DocUtils.HasCustomAttribute(method.MethodReturnType, Consts.IsReadOnlyAttribute))
             {
                 modifiers += " readonly";
             }

mdoc/mdoc.Test/DocUtilsTests.cs

@@ -1,7 +1,7 @@
 using System.Linq;
 using mdoc.Test.SampleClasses;
+using Mono.Documentation;
 using Mono.Documentation.Updater;
-using Mono.Documentation.Updater.Frameworks;
 using NUnit.Framework;
 using System.Xml;
 
@@ -144,5 +144,19 @@ random text
             var result = DocUtils.IsEiiIgnoredMethod(member, member.Overrides[0]);
             Assert.IsTrue(result);
         }
+
+        [Test]
+        public void HasCustomAttributeTest()
+        {
+            Assert.IsFalse(DocUtils.HasCustomAttribute(null, ""));
+
+            var type = GetType(typeof(SampleClasses.RefStruct));
+            Assert.IsFalse(DocUtils.HasCustomAttribute(type, Consts.IsReadOnlyAttribute));
+            Assert.IsTrue(DocUtils.HasCustomAttribute(type, Consts.IsByRefLikeAttribute));
+
+            type = GetType(typeof(SampleClasses.ReadOnlyRefStruct));
+            Assert.IsTrue(DocUtils.HasCustomAttribute(type, Consts.IsReadOnlyAttribute));
+            Assert.IsTrue(DocUtils.HasCustomAttribute(type, Consts.IsByRefLikeAttribute));
+        }
     }
 }

mdoc/mdoc.Test/FormatterTests.cs

@@ -387,6 +387,22 @@ namespace mdoc.Test
             Assert.AreEqual(true, flag);
         }
 
+        [Test]
+        public void CSharpRefStructTest()
+        {
+            var type = GetType(typeof(SampleClasses.RefStruct));
+            var typeSignature = formatter.GetDeclaration(type);
+            Assert.AreEqual("public ref struct RefStruct", typeSignature);
+        }
+
+        [Test]
+        public void CSharpReadOnlyRefStructTest()
+        {
+            var type = GetType(typeof(SampleClasses.ReadOnlyRefStruct));
+            var typeSignature = formatter.GetDeclaration(type);
+            Assert.AreEqual("public readonly ref struct ReadOnlyRefStruct", typeSignature);
+        }
+
         #region Helper Methods
         string RealTypeName(string name){
             switch (name) {

mdoc/mdoc.Test/SampleClasses/ReadOnlyRefStruct.cs

@@ -0,0 +1,7 @@
+namespace mdoc.Test.SampleClasses
+{
+    public readonly ref struct ReadOnlyRefStruct
+    {
+
+    }
+}

mdoc/mdoc.Test/SampleClasses/RefStruct.cs

@@ -0,0 +1,7 @@
+namespace mdoc.Test.SampleClasses
+{
+    public ref struct RefStruct
+    {
+
+    }
+}